docs: Clarify Object custom-property name collision in class reference

[basteez]

What this changes

Adds a clarifying Note: to the _get_property_list() description in the Object class reference (doc/classes/Object.xml), warning that a custom property's name must not collide with an existing member variable or built-in property (including @export vars).

Why

Reported in #64227: a user defined a real member variable and returned a property with the same name from _get_property_list(), then overrode _set() to react to changes. Their _set() was never called, so the inspector never refreshed. Prefixing the name (e.g. /my_property) made it work, because the name no longer matched a real member.

This is intended behavior, confirmed by @HolonProduction in the issue thread — _get()/_set() are not called for built-in properties, and a _get_property_list() entry whose name matches a member collides with that built-in property.

The existing _get()/_set() notes already state the "not called for built-in properties" half. What was missing is the connection: don't reuse a member variable's name for a custom property. This PR adds exactly that, at the method that adds the names.

The note

The name of a property added here must not match an existing member variable or built-in property (including one defined with @export). If it does, the engine handles it as that built-in property, and your _get() and _set() overrides are not called for it.

Prose-only (no code sample), so it can't drift out of sync across the GDScript/C# examples. It frames the rule generally rather than documenting the / prefix as a supported feature, since that's an incidental side effect of the name no longer matching a member.

Scope

Docs-only. No C++, no scripting API, no other XML files. The GDScript tutorial prose quoted in the report lives in godot-docs and could get a matching clarification as a follow-up there.

Testing

• make_rst.py doc/classes modules platform --dry-run reports no warnings or errors; all [method ...] / [annotation ...] references resolve.
• git diff --stat shows only doc/classes/Object.xml changed.

Closes #64227

[akien-mga]

AI generated.